Yes, the phrase "I came home at about one o'clock" is grammatically correct. It follows a subject-verb-object structure and conveys a clear message about the time of arrival.
I am, you are, he/she/it is, we are, they are.
It is grammatically correct to say: There is nothing wrong with this machine.It is not grammatically correct to say: Will it is be grammatically correct to say ....The correct way to write that or say that would be: Would it be grammatically correct to say....
There isn't one that is grammatically correct.
Yes it is.
Certainly. If one were to make a comparison saying "He can run as quick as a cheetah" then it would be grammatically correct.
The second one is more correct.
Yes. That's correct.
To be clear, one's answer should be grammatically correct.
Both "which date" and "what date" are grammatically correct. You can use either one depending on your personal preference or the context of the sentence.
Both are grammatically correct, but "do not feel" is better usage than "are not feeling."
"Respectful to his teacher" is correct.